Helmet with air flow rib structure



FIG. 1 is a rear oblique view of a helmet with air flow rib structure showing my new design;

FIG. is a front oblique view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a side elevation view thereof, the opposite side being a mirror image;

FIG. 5 is a front elevation view thereof;

FIG. 6 is a rear elevation view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for a helmet with air flow rib structure, as shown and described. 